/*
 *  Licensed to the Apache Software Foundation (ASF) under one
 *  or more contributor license agreements.  See the NOTICE file
 *  distributed with this work for additional information
 *  regarding copyright ownership.  The ASF licenses this file
 *  to you under the Apache License, Version 2.0 (the
 *  "License"); you may not use this file except in compliance
 *  with the License.  You may obtain a copy of the License at
 *  
 *    http://www.apache.org/licenses/LICENSE-2.0
 *  
 *  Unless required by applicable law or agreed to in writing,
 *  software distributed under the License is distributed on an
 *  "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
 *  KIND, either express or implied.  See the License for the
 *  specific language governing permissions and limitations
 *  under the License. 
 *  
 */
package simpipe.examples;

import java.io.Serializable;

/**
 * A tennis ball which has TTL value and state whose value is one of 'PING' and 'PONG'.
 * 
 * @author The Apache Directory Project (mina-dev@directory.apache.org)
 * @version $Rev: 555855 $, $Date: 2007-07-13 12:19:00 +0900 () $
 */
public class TennisBall implements Serializable {
	/**
	 * 
	 */
	private static final long serialVersionUID = 1L;

	private final boolean ping;

	private final int ttl;

	/**
	 * Creates a new ball with the specified TTL (Time To Live) value.
	 */
	public TennisBall(final int ttl) {
		this(ttl, true);
	}

	/**
	 * Creates a new ball with the specified TTL value and PING/PONG state.
	 */
	private TennisBall(final int ttl, final boolean ping) {
		this.ttl = ttl;
		this.ping = ping;
	}

	/**
	 * Returns the TTL value of this ball.
	 */
	public int getTTL() {
		return ttl;
	}

	/**
	 * Returns the ball after {@link TennisPlayer}'s stroke. The returned ball has decreased TTL value and switched PING/PONG state.
	 */
	public TennisBall stroke() {
		return new TennisBall(ttl - 1, !ping);
	}

	/**
	 * Returns string representation of this message (<code>[PING|PONG]
	 * (TTL)</code>).
	 */
	@Override
	public String toString() {
		if (ping) {
			return "PING (" + ttl + ")";
		} else {
			return "PONG (" + ttl + ")";
		}
	}
}